Tuber pathogenicity of Macrophomina phaseolina strain 3a isolated from rotten cassava tuber from farm lands in Osogbo, Osun State, Nigeria, its virulence genes and ADMET properties.

Abstract

Macrophomina phaseolina is a pathogen that causes an opportunistic disease that spreads by soil and seeds and affects more than 500 different plant species, like fruits, trees, and row crops. Mycotoxins, such as phaseolinic acid, and phaseolinone, are produced by M. phaseolina isolates in previous investigations; however, the production of these mycotoxins seems to vary depending on the host and the region. In this study, Macrophomina phaseolina strain 3A was isolated from rotten cassava tuber and identified using the analysis of the sequences of the internal transcribed spacer region. The isolate was inoculated on a fresh healthy cassava tuber at 25°C and tuber-rotting potential was monitored for 4 weeks. Virulence genes MPH_06603, MPH_06955, and MPH_01521 were determined with designed primers, and secondary metabolites were characterized by FTIR and GCMS. The rotten tuber effect was observed from the 2nd week of the experiment with severe tuber rot and weight reduction. The PCR showed the presence of MPH_06603 virulence gene. The GCMS showed N-Methylpivalamide (115.0m/z), Butane, 1,4-dimethoxy- (119.0m/z), and 5-Hydroxymethylfurfural (126.0m/z) were the predominant metabolites produced by the pathogen. The compounds in the metabolites inhibit CYP3A4 enzymes, cause eye irritation, and Human Ether-a-go-go-related gene inhibition. This study revealed that M. phaseolina was responsible for the cassava tuber rot which leads to a lower yield of farm produce. The metabolites produced are toxic and unsafe for human consumption. It is suggested that farmers should destroy any cassava affected by this pathogen to prevent its toxic effects on humans and animals.